Continuous oxygen steel making process

ABSTRACT

THIS INVENTION IS TO PROVIDE A PROCESS AND APPARATUS FOR OXIDIZING SUCH IMPURITIES AS CARBON, SILICON, SULFUR AND PHOSPHORUS IN A MOLTEN PIG IRON BY INJECTING OXYGEN FROM THE SIDE OF THE MOLTEN PIG IRON WHILE IT IS BEING MADE TO FLOW DOWN A SERIES OF SHELF MEMBERS IN A VERTICAL REFINING CHAMBER.

Jill. 19, 1971 TATSUQ KURATOMI 3,556,775

' CONTINUOUS OXYGEN STEEL MAKING PROCESS Filed Jan. :3, 1968 INVEN'H )R 'l'I/ISUO KUHATOMI A ()RNIZ'Y United States Patent O U.S. CI. 75-60 1 Claim ABSTRACT OF THE DISCLOSURE This invention is to provide a process and apparatus for oxidizing such impurities as carbon, silicon, sulfur and phosphorus in a molten pig iron by injecting oxygen from the side of the molten pig iron while it is being made to flow down a series of shelf members in a vertical refining chamber. 1

BACKGROUND OF THE INVENTION This invention relates to continuous oxygen steel making processes and apparatus for the same.

An object of the present invention is to provide a steel making process high in the productivity and low in the producing cost by continuously oxygen steel making a continuously fed molten pig iron so as to be a molten steel.

A further object of the present invention is to provide a steel making apparatus high in the durability and low in the equipment cost.

SUMMARY OF THE INVENTION This invention relates to steel making process and apparatus for continuously refining a molten pig iron, characterized in that the molten pig iron is made to flow down a series of steps or shelves. The contact of the molten pig iron with the oxygen is efficiently performed by injecting oxygen from the side of the falling molten pig iron so that such impurities as carbon, silicon, sulfur and phosphorus in the molten pig iron may be oxidized.

That is to say, oxygen is jetted and passed across a falling molten pig iron so that the molten pig iron may fall in a splashed state and many of such states are continued on the plurality of steps so that the contact of the molten pig iron and oxygen with each other may be repeated several times in series. When the flow and fall of the molten pig iron and crossing passage of the oxygen are thus continuously carried out several times on the steps, the molten pig iron will be continuously agitated, limestone or any other slagging agent will be continuously repeatedly mixed with the molten pig iron. Therefore silicon oxide, phosphorus oxide and other oxides accumulated in the molten pig iron will be caught by the slag of the molten slagging agent and will thus move into the slag out of the molten pig iron, and at the same time such gaseous oxides produced by reacting with the oxygen as carbon oxide and sulfur oxide will be discharged out of the molten pig iron. The molten pig iron will thus be gradually reduced in the carbon content so as to be made into a molten steel.

Further, in the present apparatus for fully carrying out such oxidizing operation, each chamber opened only in the front is formed as a unit device for bringing oxygen into contact with a molten pig iron by providing side walls and a rear wall between vertically adjacent upper and lower shelves so that a wall part may be formed of the molten pig iron falling in the form of a screen from the front edge of the upper shelf in the opened front, the chamber may be closed in an air-tight state, an oxygen feeding orifice for pressing in compressed oxygen is made P CC in the rear wall or side wall of such chamber so that this chamber may be a compressed oxygen chamber, the thus formed device is used as a unit oxygen steel making device and a plurality of such unit devices are connected in the form of steps so that any desired oxygen steel making may be carried out continuously.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing is a vertically sectional view showing an apparatus for working the continuous oxygen steel making process according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT The apparatus and process of this invention shall be explained with reference to the drawing. 1 is a steel making apparatus body or refining chamber of the present invention. In thefupper part of the body is provided a slagging agent feeder 2. Within said steel making apparatus body 1, there are molten pig iron flowing shelves 11, 21, 31 provided continuously in the form of several steps as main bodies of steel making devices for working the continuous oxygen steel making process of the present invention. In each space part between the 5 vertically adjacentfupper shelf and lower shelf, there is -formed an oxygen chamber 17, 27, 37 provided with side walls 16, 1'6, 26, 26', 36, 36' on both sides and opened only in the front with the rear wall 15, 25, 35 the lower surface 14, 24, 34 of the upper shelf and the floor surface 22, 32, 42 of the lower shelf.

Further, in each rear wall 15, 25, 35 is provided a compressed oxygen feeding orifice 18, 28, 38 connected with a compressed oxygen feeding main pipe 5. 3 is a molten pig iron pool located in the upper part. 4 is a molten steel pool located in the lower part.

Now, if a molten pig iron 6 is continuously fed to this steel making apparatus through a molten pig iron flowing inlet in the uppermost part and a slagging agent 7 such as limestone is fed and added to it in the molten pig iron pool 3 in the upper part from a slagging agent feeder 2, the molten pig iron to which this slagging agent has been added will lie on the floor surface 12 of the shelf 11 in the uppermost position. The molten material will then fall along the front edge 13 of the shelf 11. Then it falls in the form of a screen down the opened part in the front of the oxygen chamber 17 and will tend to air-tightly close the oxygen chamber 17. However, as compressed oxygen fed through the compressed oxygen feeding main pipe 5 is being jetted into the oxygen chamber 17 through the orifice 18, the above mentioned molten pig iron in the form of a screen will be blown away by this compressed oxygen so as to be flowing drops and splashes and will fall onto the floor surface 22 of the lower shelf 21 while exposing a large surface of contact with the oxygen.

In such case, such impurities as carbon, silicon, sulfur and phosphorus in the molten pig iron will be oxidized by contact with the oxygen, whereby the produced gaseous oxides such as carbon oxide and sulfur oxide will be discharged out of the molten 'pig iron. The silicon oxide and phosphorus oxide remaining in the molten pig iron will be caught by the slag which is a melt of the slagging agent mixed with the molten pig iron and will then melt into the slag.

When such reaction cycle of the molten pig iron with oxygen is repeated as the molten pig iron falls from one shelf down to the next shelf. The content of carbon and the content of other impurities in the molten pig iron is reduced to the desired contents. The compressed oxygen feeding orifice of the shelf should then be closed to stop the injection of oxygen. Therefore, on the shelves below it, the melt which has already become a molten steel will merely flow and fall until it flows into the molten steel' pool 4 in the lowermost part. In this molten steel pool 4 the molten steel will flow slowly at a reduced flow velocity, the slag will fioat out of the molten material and separate from the molten steel. The molten steel 8 and the slag 9 will thus continuously flow out through respective flowing outlets.

I claim: 1. A continuous flow process for producing steel from a molten pig iron solution in a vertical refining chamber which includes a large number of shelf members having horizontal and vertical surfaces comprising the stages of introducing a slagging agent in a pool of molten pig iron at the top of the chamber,

causing the molten metallic material to flow from the horizontal surface over the edge of the first shelf member to form a screen of free falling droplets, subjecting the screen of droplets to jetted streams of an oxidizing gas which are directed at right angles to the screen, the droplets in this manner forming a shallow pool on the horizontal surface of the second shelf member and then pouring over the edge of the second shelf, the molten metallic material as a result of the above mentioned operations thereon having a turbulence and cascading characteristic, repeating the cycle stages of jetting oxygen to the 4 screen of droplets, the formation of the pool on the horizontal shelf surface and the descent of the molten metallic material with respect to each individual shelf member for oxidizing the impurities from the molten metallic material, and the collection of the resulting refined steel material from the lowest shelf member of the vertical chamber.

References Cited UNITED STATES PATENTS 2,600,575 6/1952 Reinartz et al 7546X 2,639,984 5/1953 Jordan 7560X 2,693,411 11/1954 Cremer 7546 2,819,160 1/1958 Bannister et al. 7560UX 2,915,380 12/1959 Hilty 7560X 2,969,282 1/1961 Churcher 7560 FOREIGN PATENTS 817,783 8/1959 Great Britain 7560 HYLAND BIZOT, Primary Examiner G. K. WHITE, Assistant Examiner US. Cl. X.R. 7546 

